Automated document factories are mechanized assembly lines that may print, collate, label, sort, or otherwise process documents, such as bills, statements and advertisements, to be assembled for mass mailing. Examples of automated document factories are disclosed in U.S. Pat. Nos. 5,510,997 and 5,608,639, which are incorporated herein by reference. In an automated document factory, the documents to be assembled or otherwise processed often are identified by various symbologies printed on the documents, such as barcodes or dataglyphs, several of which are discussed in U.S. Pat. Nos. 5,276,315, 5,329,104 and 5,801,371, which are also incorporated herein by reference.
Data glyphs can be preprinted on stock permit automated identification of print stock to insure that the correct materials are being used. Data glyphs can also be printed on the stock as it goes through the printer to identify the intended recipient of the document or some other materials that should be associated with the printed item. By reading the printed glyphs during subsequent processing, collation and handling of documents can be verified and automated.
Documents in automated document factories are moved on conveyer belts, usually at high speed. As a result it is necessary to scan the documents quickly and process the acquired data in a minimum time. Preferably, a proximity sensor is used to monitor when a document or other object to be read has moved within range of a camera of the machine vision system. When the proximity sensor detects a document, a pulsed illuminator is triggered so that the camera may obtain a clear picture of the document to be read even though the document is moving continuously. The rapid flash of the illuminator "freezes" the document for the camera. Examples of pulsed LED and other light sources are disclosed in U.S. Pat. Nos. 4,542,528, 5,135,160, 5,349,172 and 5,600,121 which are incorporated herein by reference.
Unfortunately, although existing systems permit scanning of documents at sufficient rates, the process of analyzing the scanned data to extract the data encoded in data glyphs has been an impediment to rapid document processing. In particular, with existing systems, there is no feasible process for extracting the data glyph data from scanned images quickly enough to allow for real time processing of each document as it moves through a document factory.